What foods can you eat?

Ewoldt says nuts, seeds, full-fat cheese and other dairy products, plain Greek yogurt, nonstarchy and fibrous vegetables, oils, along with smaller amounts of meats, eggs and fish, become keto diet mainstays.

You'll need to sharply limit carbohydrates, including bread and baked goods, sweets, pasta, breakfast cereals, starchy vegetables like potatoes, sweet potatoes, corn and peas, beans, fruit, and beer.

Thirsty? Reach for the water bottle, or enjoy some sparking water. Unsweetened coffee and tea also are allowed. Minimize alcohol intake; if you do drink, choose low-carb options (vodka, tequila) and soda water as a mixer.